Effect of Withdrawal Rates on Microstructure and Creep Strength of a Single Crystal Superalloy Processed by LMC

• Published in: Journal of materials science & technology Vol. 26; no. 4; pp. 306 - 310
• Main Authors: Liu, Chengbao, Shen, Jian, Zhang, Jian, Lou, Langhong
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.04.2010
• Subjects: Eutectic; Liquid-metal-cooling; Single crystal superalloy; Withdrawal rate; 单晶高温合金; 定向凝固高温合金; 微观结构; 蠕变断裂寿命; Single crystal superalloy; Withdrawal rate; Eutectic; Liquid-metal-cooling
• ISSN: 1005-0302; 1941-1162
• DOI: 10.1016/S1005-0302(10)60050-3

A nickel base single crystal （SC） superalloy was directionally solidified using liquid metal cooling （LMC） process at various withdrawal rates. The microstructure was refined as increasing the withdrawal rate from 3 to 12 mm/min. However, higher withdrawal rate of 15 mm/min induced the formation of stray grains. Size and volume fraction of the eutectics were found to decrease with the increasing in withdrawal rate. After solution heat treatment at 1250℃, un-dissolved eutectic was observed in specimens. High temperature creep rupture life was observed to be very sensitive to the fraction of these remaining eutectics. Creep rupture tests at 1000℃/235 MPa showed that refined microstructure and low fraction of the remaining eutectic lead to significant improvement of the rupture life.